‘Whatever happened to austerity?’ asked the splash on today’s Daily Mail. It’s a reasonable question. As Paul laid out this morning, the Autumn Statement used improved OBR forecasts to retreat from the hard choices, expending new-found wriggle room on relaxing spending restraints rather than banking it as a down-payment on balancing the books.

Some of that is undoubtedly the Chancellor’s responsibility. Presented with a choice between doing the boring, responsible thing and doing the glitzy, imprudent thing, he opted for the roar of the crowd over the quiet approval of the bank manager. Perhaps he had the forthcoming leadership race in mind, perhaps he has simply tired of being the strict parent and wanted to be the good guy for once. Most likely it was a combination of the two.

That was Osborne’s decision to make – to govern is to choose, as Nigel Lawson said, and he surely knows that if he becomes Prime Minister then his term in that office will be helped or hindered by the legacy of his time as Chancellor.

But the wider Conservative Party, and the centre-right movement around it, must also interrogate and scrutinise its own responsibility for this breach of fiscal discipline. For it was Conservative MPs, thinkers and campaigners who established the conditions for Osborne’s about-turn. With a slim majority, even a small rebellion can becalm the Government or even change its course. That places a responsibility on individual MPs to pick their battles extremely carefully.

Every single member of the Parliamentary Conservative Party fought the recent election on a platform of deficit reduction and – eventual – elimination. Every single one will have argued on the doorstep or in the media that the nation must live within its means, that spending must be reduced and that new borrowing today is the infliction of extra taxes on our children when they join the workforce.

And yet in this battle – the first major austerity clash of the first majority Conservative Government in two decades – some of them wobbled. Enough of them did so, in fact, for the Chancellor to either feel compelled to abandon a money-saving drive, or for the temptation of being Mr Nice Guy to reach and seduce him.

I’m not arguing that the tax credits cut was the one and only thing the Government could have done to save money, or even necessarily the right thing to do. Conservative MPs did not have a responsibility to support it no matter what – but if they wanted Plan A to be dropped then they did have a responsibility to press for a Plan B to save the same amount of money. No real alternative was presented as a way to avoid the political pain, so instead we now have a weakened fiscal plan.

As a result, there is now talk about whether the Chancellor has lost his mojo for austerity – whether five years up a ladder trying to fix the roof while the sun still shines has cost him his head for heights. He has certainly allowed his focus on the overall mission to waver to a degree not previously seen.

But we should also be asking whether the Parliamentary Conservative Party has lost its commitment to balancing the books. After all, it is at this point – still years away from the next election – that the truly difficult decisions are meant to be made, but the hard-won Tory majority is already proving to be fragile under pressure. Too many of Osborne’s colleagues neither stuck to their guns nor offered money-saving alternatives to the policy they were opposing – in doing so, they set the conditions under which the Chancellor flinched.